A transitive verb has an object. An object is a word or group of words that receive the action of the verb. An intransitive verb has no object. Since your sentence has an object, "all the answers on the test",the verb "knew" is transitive.

In this particular sentence, there is only one verb, "knew." Now you need to figure out whether it is transitive or intransitive. Along with the other answers you've already gotten, you need to remember that a transitive verb shows action. In your sentence, the action being expressed is that of knowing something.

The transitive verb tells us what action the subject performs on the direct object. In your example, Jessie's action is to know the answers.

The queston you have asked is very simple. For example you may be aware of the meaning of the word ``Transit``. It means ``Passing through``.If the verb is actually a transitive verb,there must be something or an object that passes through the object to complete what a subject means. In your sentence, Jessie knew all the answers on the test, the phrase All the answers on the test passes through the verb ``Knew`` ,so the verb knew is the transitive verb.